Apparatus for separating particles from fluid flow

ABSTRACT

Apparatus ( 10, 110, 210, 310 ) for separating particles from a fluid flow comprises an upstream cyclonic separator ( 12, 112, 212, 312 ) and a plurality of downstream cyclonic separators ( 26, 126, 226, 326 ) arranged in parallel with one another. Each of the downstream cyclonic separators ( 26, 126, 226, 326 ) projects, at least in part, into the interior of the upstream cyclonic separator ( 12, 112, 212, 312 ). This arrangement provides a compact and economic apparatus which is particularly suitable for applications such as vacuum cleaners.

[0001] The present invention relates to apparatus for separatingparticles from a fluid flow. Particularly, but not exclusively, theinvention relates to apparatus for separating particles, such as dirtand dust particles, from an airflow.

[0002] It is well known to separate particles, such as dirt and dustparticles, from a fluid flow using a cyclonic separator. Known cyclonicseparators are used in vacuum cleaners, for example, and have been knownto comprise a low efficiency cyclone for separating fluff and relativelylarge particles and a high efficiency cyclone located downstream of thelow efficiency cyclone for separating the fine particles which remainentrained within the airflow (see, for example, EP 0 042 723B). It isalso known to provide, in vacuum cleaning apparatus, an upstreamcyclonic separator in combination with a plurality of smaller,downstream cyclonic separators, the downstream cyclonic separators beingarranged in parallel wilt one another. An arrangement of this type isshown and described in U.S. Pat. No. 3,425,192 to Davis.

[0003] In vacuum cleaner applications, particularly in domestic vacuumcleaner applications, it is desirable for the appliance to be made ascompact as possible without compromising the performance of theappliance. It is also desirable for the efficiency of the separationapparatus contained within the appliance to be as efficient as possible(ie. to separate as high a proportion as possible of very fine dustparticles from the airflow). It is therefore an object of the presentinvention to provide improved apparatus for separating particles from afluid flow. It is a further object of the present invention to provideapparatus for separating particles from a fluid flow having an improvedseparation efficiency or pressure drop and having a compact arrangement.It is a further object of the invention to provide improved apparatusfor separating particles from a fluid flow and suitable for use in adomestic vacuum cleaner.

[0004] The invention provides apparatus for separating particles from afluid flow comprising an upstream cyclonic separator and a plurality ofdownstream cyclonic separators arranged in parallel with one another,characterised in that each of the downstream cyclonic separatorsprojects, at least in part, into the interior of the upstream cyclonicseparator.

[0005] The arrangement of the invention makes use of the high separationefficiency achievable by a plurality of parallel cyclones whilst alsoallowing the combination of the upstream and downstream cyclonicseparators to be compactly packaged. This allows the apparatus to beutilised in an appliance such as a domestic vacuum cleaner.

[0006] Preferably, each of the downstream cyclonic separators projectsinto the interior of the upstream cyclonic separator by a distance equalto at least one third of the length of the respective downstreamcyclonic separator. More preferably, each of the downstream cyclonicseparators projects into the interior of the upstream cyclonic separatorby a distance equal to at least half of the length of the respectivedownstream cyclonic separator. Still more preferably, each of thedownstream cyclonic separators projects into the interior of theupstream cyclonic separator by a distance equal to at least two thirdsof the length of the respective downstream cyclonic separator. In apreferred embodiment, that each of the downstream cyclonic separators islocated substantially wholly within the upstream cyclonic separator.These arrangements give rise to convenient and compact packagingsolutions.

[0007] Embodiments of the invention will now be described with referenceto the accompanying drawings, wherein:

[0008]FIG. 1 is a schematic perspective view of apparatus according to afirst embodiment of the present invention:

[0009]FIG. 2a is a longitudinal section through apparatus according to asecond embodiment of the present invention;

[0010]FIG. 2b is a sectional view taken along the line II-II of FIG. 2a;

[0011]FIG. 3a is a longitudinal section taken through apparatusaccording to a third embodiment of the present invention;

[0012]FIG. 3b is a section taken along the line III-III of FIG. 3a;

[0013]FIG. 4a is a longitudinal cross-section through apparatusaccording to a fourth embodiment of the present invention and takenalong the line IV-IV of FIG. 4b;

[0014]FIG. 4b is a transverse cross-section taken along the line IV-IVof FIG. 4a;

[0015]FIG. 5a is a longitudinal cross-section through apparatusaccording to a fifth embodiment of the present invention and taken alongthe line V-V of FIG. 5b; and

[0016]FIG. 5b is a transverse cross-section taken along the line V-V ofFIG. 5a.

[0017] The basic principle of the present invention is illustrated inFIG. 1. In FIG. 1, the apparatus 10 for separating particles from afluid flow comprises an upstream cyclone 12 having an upper end 14 and abase 16. A side wall 18 extends between the upper end 14 and the base16. The side wall 18 is frusto-conical so that the upstream cyclone 12tapers outwardly away from the upper end 14. A tangential inlet 20 isprovided in the side wall 18 adjacent the upper end 14. The tangentialinlet 20 is capable of delivering particle-laden fluid to the interiorof the upstream cyclone 12 in a direction which is tangential to theside wall 18 so as to set up a swirling flow in the interior of theupstream cyclone 12. In many of the applications for which the apparatus10 is intended to be used, the fluid is air and the particles are dirtand dust such as will be found in a domestic environment.

[0018] The upstream cyclone 12 has an outlet (not shown) which islocated centrally of the upper end 14 and communicates with the interiorof the upstream cyclone 12. The outlet comprises a generally cylindricalpipe which extends vertically upwardly from the upper end 14 of theupstream cyclone 12. The outlet divides into four inlet conduits 24 in asymmetrical and even manner. Each inlet conduit 24 is dimensioned andarranged so as to receive one quarter of any fluid flow traveling alongthe outlet from the upstream cyclone 12.

[0019] Each inlet conduit 24 communicates with a downstream cyclone 26.Each downstream cyclone 26 has an upper cylindrical portion 28 withwhich the respective inlet conduit 24 communicates in a tangentialmanner. A frusto-conical cyclone portion 30 depends from each uppercylindrical portion 28 and has an open cone opening 32 remote therefrom.Each downstream cyclone 26 has a longitudinal axis (not shown) aboutwhich the respective upper cylindrical portion 28 and frusto-conicalcyclone portion 30 are arranged. The four downstream cyclones 26 areinclined to the vertical so that their longitudinal axes approach oneanother in a downward direction. The cone openings 32 are thereforearranged close to one another and symmetrically about a longitudinalaxis of the upstream cyclone 12.

[0020] Each of the frusto-conical cyclone portions 30 passes through theupper end 14 of the upstream cyclone 12. In the upper end 14, fourappropriately-sized apertures 31 are arranged. Each of thefrusto-conical cyclone portions 30 is fixed to the rim of the respectiveaperture 31 in a manner which maintains a seal therebetween.

[0021] A cylindrical collector 34 is arranged inside the upstreamcyclone 12. The cylindrical collector 34 extends between the base 16 ofthe upstream cyclone 12 and meets the frusto-conical cyclone portions.30 of the downstream cyclones 26 at a location which is slightly abovethe cone openings 32. Although it is not shown in FIG. 1, thecylindrical collector 34 has an upper face through which the lower endsof the frustoconical cyclone portions 30 pass in such a manner as toseal the interior of the cylindrical collector 34 from the remainder ofthe interior of the upstream cyclone 12.

[0022] Each of the four downstream cyclones 26 has an outlet conduit 36located centrally of the respective upper cylindrical portion 28. Theoutlet conduits 36 meet at a junction 38 to form a combined outlet 40.Fluid entering the apparatus 10 via the tangential inlet 20 is expelledvia the combined outlet 40. In some applications, for example in vacuumcleaner applications, the combined outlet 40 will be connected in aknown manner to a vacuum source.

[0023] The apparatus 10 described above operates in the followingmanner. A fluid flow in which particles are entrained enters theapparatus 10 via the tangential inlet 20. The orientation of thetangential inlet 20 causes the fluid flow to follow a helical pathwithin the upstream cyclone 12 so that the fluid flow travels downwardlytowards the base 16. Relatively large particles entrained within theincoming fluid flow are deposited in the lower portion of the interiorof the upstream cyclone 12 adjacent the base 16. The fluid flow, inwhich smaller particles remain entrained, moves inwardly and upwardlytowards the upper end 14 of the upstream cyclone 12. The fluid flowexits the upstream cyclone 12 via the outlet (not shown) along which thefluid flow travels until it is split into four separate fluid flowswhich travel along the inlet conduits 24 to the downstream cyclones 26.When each portion of the fluid flow reaches the upper cylindricalportion 28 of the respective downstream cyclone 26, it again follows ahelical path therein in view of the tangential orientation of the inletconduit 24. The fluid flow then follows a further helical path down thefrusto-conical cyclone portion 30 of the downstream cyclone 26 and,during this time, many of the fine particles are separated from thefluid flow. The separated fine particles are deposited inside thecylindrical collector 34 whilst the particle-free fluid leaves thedownstream cyclone 26 via the outlet conduit 36. The separate fluidflows are recombined at the junction 38 and leave the apparatus 10 viathe combined outlet 40.

[0024] In this embodiment, the downstream cyclones 26 project into theinterior of the upstream cyclone 12 to such an extent that approximatelyone third of the length of each downstream cyclone 26 is located insidethe upstream cyclone 12. The arrangement is compact and efficient andtherefore suitable for use in an application where dimensions are to bekept as small as possible. An example of such an application is adomestic vacuum cleaner in which considerations of size and weight areof considerable importance. In such an application, the combined outlet40 will be connected to a vacuum source and the tangential inlet 20 willbe connected to a dirty air inlet of the vacuum cleaner. In a cylindervacuum cleaner, the dirty air inlet will take the form of a hose andwand assembly. In an upright vacuum cleaner, the dirty air inlet willtake the form of a cleaner head forming part of the vacuum cleaner as awhole. Arrangements can, of course, be made within an upright vacuumcleaner for conversion to operation in a cylinder mode. The mode ofoperation of the vacuum cleaner has no effect on the apparatusillustrated above.

[0025] In all vacuum cleaner applications, the apparatus 10 describedabove will require periodic emptying of separated particles. One way toachieve this would be to arrange for the base 16 to be made removablefrom the side wall 18 for emptying purposes. In this case, it isspecifically advantageous if the cylindrical collector 34 is formedprimarily by way of a cylindrical wall which meets and abuts against thebase 16. The interior of the cylindrical collector 34 is thereforedelimited at the lower end by the base 16. This allows both thecylindrical collector 34 and the remainder of the upstream cyclone 12 tobe emptied simultaneously. Alternatively, the upstream cyclone 12 can bemade separable at a position between the upper end 14 and the base 16,preferably in the vicinity of the upper end 14. The point of separationis advantageously located so that the upper end 14 and a portion of theside wall 18 incorporating the tangential inlet 20, together with thedownstream cyclones 26, are separable from the remainder of the sidewall 18 together with the cylindrical collector 34.

[0026] A second embodiment of the invention is shown in FIGS. 2a and 2b. In this embodiment, the upstream cyclone 112 again has an upper end114 and a base 116. The side wall 118 is cylindrical so that the overallshape of the upstream cyclone 112 is also cylindrical. A tangentialinlet 120 is again provided adjacent the upper end 114 of the upstreamcyclone 112.

[0027] In this second embodiment, only two downstream cyclones 126 areprovided. Therefore, the outlet 122 from the upstream cyclone 112 isdivided into only two separate inlet conduits 124. The inlet conduits124 each communicate in a tangential manner with the upper cylindricalportion 128 of the respective downstream cyclone 126.

[0028] In this embodiment, the longitudinal axis 142 of each downstreamcyclone lies parallel to the longitudinal axis 144 of the upstreamcyclone 122. Each downstream cyclone 126 has a generally cylindricalcollector 134 depending from the frusto-conical cyclone portion 130.Each cylindrical collector 134 extends downwardly from thefrusto-conical cyclone portion 130 just above the cone opening 132 tothe base 116 of the upstream cyclone 112. Each downstream cyclone 126also has an outlet conduit 136 which is located centrally of therespective upper cylindrical portion 128 and which merges with the otheroutlet conduits 136 to form a combined outlet 140.

[0029] The operation of the apparatus 110 illustrated in FIGS. 2a and 2b is similar to that of the apparatus 10 shown in FIG. 1. Fluid in whichparticles requiring separation are entrained enters the cyclone 112 viathe tangential inlet 120. The fluid follows a helical path down thecylindrical side wall 118 of the upstream cyclone 112 and largerparticles are deposited inside the upstream cyclone 112 adjacent thebase 116. Partially cleaned fluid then leaves the upstream cyclone 112via the outlet 122 and the fluid flow is then divided into two separatefluid flows. Each separate fluid flow is then conducted to a downstreamcyclone 126 in which the fluid flow follows a helical path about theupper cylindrical portion 128 and the frusto-conical cyclone portion 130during which time the fluid flow is accelerated to high angularvelocities. In this way, fine particles are separated from the fluidflow and deposited in the cylindrical collectors 134. The cleaned fluidflow leaves the downstream cyclones 126 via the outlet conduits 136 and,subsequently, via the combined outlet 140.

[0030] As can be seen from FIG. 2a, the downstream cyclones 126 projectinto the upstream cyclone 112 through the upper end 114 thereof. Thearrangement is such that the downstream cyclones 126 project into theupstream cyclone 112 to such an extent that approximately two thirds ofthe length of each downstream cyclone 126 is located in the interior ofthe upstream cyclone 112. This arrangement provides an extremely compactand useful arrangement in which the efficiency of the upstream cyclone112 is not compromised to any significant extent. In other respects, theapparatus 110 is similar to the apparatus 10 shown in FIG. 1 anddescribed above.

[0031] A third embodiment of the invention is shown in FIGS. 3a and 3 b.In this embodiment, as in the embodiment shown in FIG. 1, the apparatus210 comprises an upstream cyclone 212 and four downstream cyclones 226.Also, as shown in FIG. 1, the longitudinal axes 242 of the downstreamcyclones 226 are inclined towards the longitudinal axis 244 of theupstream cyclone 212. A further similarity between the embodiment shownin FIG. 1 and that shown in FIGS. 3a and 3 b is that all four of thedownstream cyclones 226 have cone openings 232 which are surrounded andenclosed by a single cylindrical collector 234.

[0032] There are two major differences between the apparatus 10 shown inFIG. 1 and the apparatus 210 shown in FIGS. 3a and 3 b. In the apparatus210 shown in FIGS. 3a and 3 b, the side wall 218 of the upstream cyclone212 is frusto-conical and tapers inwardly from the upper end 214 towardsthe base 216. Thus, the interior of the upstream cyclone 212 has agenerally inwardly-tapering configuration. The second difference betweenthe apparatus 10 shown in FIG. 1 and the apparatus 210 shown in FIGS. 3aand 3 b is that, in the apparatus 210 shown in FIGS. 3a and 3 b, eachdownstream cyclone 226 projects into the interior of the upstreamcyclone 212 to such an extent that approximately one half of each of thedownstream cyclones 226 is located inside the upstream cyclone 212.This, in combination with the inwardly-tapering shape of the upstreamcyclone 212 provides another compact and economical arrangement of theapparatus 210.

[0033] The operation of the apparatus 210 is similar to that of theapparatus previously described in detail.

[0034] A fourth embodiment of apparatus according to the invention isillustrated in FIGS. 4a and 4 b. In this embodiment, the apparatus 310includes an upstream cyclone 312 having an upper end 314 and a base 316.The base 316 comprises a central circular portion 316 a and afrusto-conical portion 316 b extending upwardly away from the centralcircular portion 316 a. A cylindrical side wall 318 extends between thefrustoconical portion 316 b of the base 316 and the upper end 314. Thetangential inlet 320 has an elongated shape as shown in FIG. 4a.

[0035] The upstream cyclone 312 has an outlet 322 arranged centrally ofthe upper end 314. The outlet 322 comprises a cylindrical chamber 322 alocated immediately beneath the upper end 314 and centrally thereof. Adepending tube 322 b communicates with the chamber 322 a and extendstherefrom towards the base 316. The depending tube 322 b is open at thelower end thereof so as to communicate with the interior of the upstreamcyclone 312.

[0036] Nine downstream cyclones 326 are equispaced about the chamber 322a and immediately beneath the upper end 314 of the upstream cyclone 312.An inlet conduit 324 extends between the chamber 322 a and the uppercylindrical portion 328 of each of the downstream cyclones 326. Theupper cylindrical portion 328 of each of the downstream cyclones 326 isclosed on the upper side thereof by the upper end 314 of the upstreamcyclone 312. As in previous embodiments, each inlet conduit 324communicates with the respective upper cylindrical portion 328 in such amanner that fluid entering each downstream cyclone 326 does so in atangential manner. The upstream end of each inlet conduit 324communicates with the chamber 322 a so as to form a tangential offtake(see FIG. 4b).

[0037] Each downstream cyclone 326 has a frusto-conical cyclone portion330 depending from the upper cylindrical portion 328 thereof At thelower end of each frusto-conical cyclone portion 330, a cone opening 332is provided. A collector 334 surrounds and encloses all of the coneopenings 332 so that all nine of the downstream cyclones 326 are able todeposit separated particles in the interior of the collector 334. Thecollector 334 is generally frusto-conical in shape and has an upper face334 a which is able to receive the lower ends of the frusto-conicalcyclone portions 330 of the downstream cyclones 326 so that thefrusto-conical cyclone portions 330 pass into the interior of thecollector 334. The upper face 334 a also serves to separate the interiorof the collector 334 from the remainder of the interior of the upstreamcyclone 312.

[0038] Each downstream cyclone 326 has an outlet conduit 336 arrangedcentrally of the upper cylindrical portion 328 thereof. Each outletconduit 336 passes through the upper end 314 of the upstream cyclone312. As in previous embodiments, the outlet conduits 336 merge at ajunction 338 so as to form a combined outlet 340.

[0039] Operation of the apparatus 310 is similar to the apparatuspreviously described. Fluid in which particles are entrained enters theapparatus 310 via the tangential inlet 320. The fluid (and entrainedparticles) follow a general helical path around the interior of theupstream cyclone 312 and down the side wall 318 towards the base 316.Larger particles are separated from the fluid flow and collected in theinterior of the upstream cyclone 312 between the frusto-conical walls ofthe collector 334 and the frusto-conical portion 316 b of the base 316.The partially cleaned fluid flow moves inwardly and upwardly finding itsway between the downstream cyclones 326 until it exits the upstreamcyclone 312 via the depending tube 322 b of the outlet 322. The fluidflow then enters the chamber 322 a, still rotating to some extent aboutthe longitudinal axis of the upstream cyclone 312, and is there dividedinto nine roughly equivalent fluid flows by way of the inlet conduits324. Each individual fluid flow is then passed to the upper cylindricalportion 328 of one of the downstream cyclones 326. Inside the respectivedownstream cyclone 326, the fluid flow follows a generally helical path,increasing in angular velocity as it travels down the frusto-conicalcyclone portion 330 towards the cone opening 332. Fine particles areseparated from the fluid flow during this process and the particles arethen deposited in the collector 334 whilst the cleaned fluid flow leavesthe downstream cyclone 326 via the outlet conduit 336. The nine separatefluid flows are recombined at the junction 338 and leave the apparatus310 via the combined outlet 340.

[0040] As can clearly be seen from FIG. 4a, each of the downstreamcyclones 326 is located wholly within the upstream cyclone 312. Thisarrangement is particularly compact and useful in applications such ascylinder vacuum cleaners. Several features are particularly advantageoushere: the inclusion of a frusto-conical portion of the base 316 allowsthe apparatus 310 as a whole to be inclined to the vertical withoutcompromising the overall height of the apparatus unduly. Also, thefrusto-conical shape of the collector 334 increases the volume of theportion of the interior of the upstream cyclone 312 in which largeparticles and debris are intended to collect. This means that, in avacuum cleaner application, the apparatus 310 can be used for asignificant period of time without requiring to be emptied.

[0041] As in previous embodiments, the apparatus 310 illustrated inFIGS. 4a and 4 b can be emptied simply by removing a portion of theupstream cyclone 312 (advantageously the majority of the side wall 318together with the collector 334) so that emptying can take place.

[0042] A fifth embodiment is illustrated in FIGS. 5a and 5 b. It is verysimilar to the fourth embodiment illustrated in FIGS. 4a and 4 b anddescribed above. Indeed, the only difference between the fourth andfifth embodiments lies in the shape of the collector 434 in whichparticles separated in the downstream cyclones 426 are deposited.Whereas the collector 334 forming part of the fourth embodiment isgenerally conical in shape, the collector 434 forming part of the fifthembodiment is generally annular in shape. The collector 434 has an outerwall 434 a and an inner wall 434 b which extend upwardly from the base416 of the upstream cyclone 412. The downstream cyclones 426 projectinto the annular space between the outer wall 434 a and the inner wall434 b to a level below the uppermost edges of the outer and inner walls434 a, 434 b. The container 434 is closed at the top between thedownstream cyclones 426 by a lid portion 434 c through which thedownstream cyclones 426 are arranged to pass. Seals (not shown) areprovided on the lid portion 434 c to cooperate with the outer surfacesof the downstream cyclones 426 when the downstream cyclones 426 arelocated as shown in FIG. 5a. The apparatus operates in a manner verysimilar to that in which the apparatus of FIGS. 4a and 4 b operates,save that the dirt and dust separated in the downstream cyclones 426 ofFIGS. 5a and 5 b is collected in the annular collector 434 instead of inthe conical collector 334 of FIGS. 4a and 4 b. When emptying of thecontainer 434 is required, the downstream cyclones 426 are withdrawnfrom the interior of the container 434 and the upstream cyclone 412,together with the inner and outer walls 434 a, 434 b, is inverted toallow the accumulated dirt and dust to be disposed of in an appropriatefashion.

[0043] It will be appreciated from the foregoing description of the fourillustrated embodiments that the invention is not limited by the shapeof the upstream cyclone or the extent to which the downstream cyclonesproject into the interior thereof. Furthermore, any convenient manner ofemptying the apparatus illustrated above can be employed. The skilledreader will also appreciate that the means by which the fluid flow isdivided and recombined does not have a material effect on thefundamental aspects of the invention. Therefore, modifications andvariations to these and other aspects of the embodiments illustrated areintended to fall within the scope of the claimed invention.

1. A domestic vacuum cleaner incorporating apparatus for separating dirtand dust particles from an airflow comprising an upstream cyclonicseparator and a plurality of downstream cyclonic separators arranged inparallel with one another, characterised in that each of the downstreamcyclonic separators projects, partially, into the interior of theupstream cyclonic separator.
 2. A domestic vacuum cleaner as claimed inclaim 1, wherein the upstream cyclonic separator comprises a generallycylindrical chamber having a tangential or scroll entry thereto.
 3. Adomestic vacuum cleaner as claimed in claim 1, wherein the upstreamcyclonic separator comprises an outwardly tapering chamber having atangential or scroll entry thereto.
 4. A domestic vacuum cleaner asclaimed in claim 1, wherein the upstream cyclonic separator comprises aninwardly tapering chamber having a tangential or scroll entry thereto.5. A domestic vacuum cleaner as claimed in any one of the precedingclaims, wherein each of the downstream cyclonic separators comprises afrusto-conically tapering cyclone.
 6. A domestic vacuum cleaner asclaimed in any one of the preceding claims, wherein each of thedownstream cyclonic separators projects into the interior of theupstream cyclonic separator by a distance equal to substantially onethird of the length of the respective downstream cyclonic separator. 7.A domestic vacuum cleaner as claimed in claim 6, wherein each of thedownstream cyclonic separators projects into the interior of theupstream cyclonic separator by a distance equal to substantially half ofthe length of the respective downstream cyclonic separator.
 8. Adomestic vacuum cleaner as claimed in claim 7, wherein each of thedownstream cyclonic separators projects into the interior of theupstream cyclonic separator by a distance equal to substantially twothirds of the length of the respective downstream cyclonic separator. 9.A domestic vacuum cleaner for separating particles from a fluid flowsubstantially as hereinbefore described with reference to any one of theembodiments shown in the accompanying drawings.